“You’re so sentimental, Doctor. Maybe you are older than you look.” “I’m old enough to know that a longer life isn’t always a better one. In the end, you just get tired. Tired of the struggle, tired of losing everyone that matters to you, tired of watching everything turn to dust. If you live long enough, Lazarus, the only certainty left is that you’ll end up alone.” “That's a price worth paying.”

Every Doctor Who story must have a monster. That’s not an opinion as much as it is a statement of rather bizarre fact. If we look back on the previous 33 episodes of the new series, every single story has had some manner of monster, whether it’s some hideous alien beast or a hulking invasion force. Most of the time, such beasts are at the very crux of the storytelling—you can’t tell a Dalek story without a Dalek, after all—or at the very least a reasonable byproduct of the storytelling, as with the gas mask people in “The Empty Child”/“The Doctor Dances” or the possessed Ood in “The Impossible Planet”/“The Satan Pit.” But sometimes the presence of the monster is largely gratuitous, an easy way of upping the tension and filling out the episode’s running time. “Gridlock,” for instance, never really offered a proper explanation as to how the Macra got into the New New York highway, as their presence had nothing to do with the story’s central mystery of the eternal traffic jam. But the story needed a good pre-credits scare and a more visceral peril for the stranded Martha, so in the Macra went. Whether the dramatic gaps in that story were best filled by a mindless monster is debatable, but let’s not forget the old saying: When you have a hammer, every problem starts to look like a nail.

And honestly, monsters like the Macra—or the Reapers in “Father’s Day,” or even the pig-men in last week’s two-parter—may be gratuitous, but they’re not so important as to detract from the central story. How then do we deal with an episode like “The Lazarus Experiment,” in which the daft, gratuitous monster is the story? If this episode is about anything, it’s about the dangerous allure of immortality and the harm that can be done by those who value nothing but scientific advancement and personal glorification. In Professor Richard Lazarus, writer Stephen Greenhorn creates a compelling representation of this viewpoint, and Mark Gatiss—who becomes the third Doctor Who writer to also appear on the show, though the first to do so in a starring role—crafts a beautifully nuanced performance, one that presents both villainy and vulnerability in equal measure. That’s a promising scenario, and I’m not at all convinced that the best way to explore that setup is to turn Lazarus into a gigantic scorpion-like beast that feeds on people’s life energy, whatever that is.

I can understand the challenge that faced Greenhorn and the production team. Yes, the issues raised by Greenhorn’s script have the potential to be thought-provoking. The quest for immortality is one of the great mad science standbys, and the Doctor’s status as a centuries-old, regenerating alien gives him unique perspective on the matter. There’s a philosophical tension in having the Doctor condemn Lazarus’ attempt to hold back death when he himself is effectively incapable of dying of old age, and the episode occasionally leans into that tension. The Doctor claims that immortality is a curse, but that isn’t necessarily how he always feels; the great boon of eternal life is that it gives the Doctor plenty of time to get over his sadness and regret. The loss of Rose has left him in a melancholy place, but that’s nothing compared to his post-Time War trauma, and we saw him work through much of his angst over the past two seasons.

Those are all ideas worth exploring, but to do so would require this to be one hell of a talky episode. The revived Doctor Who doesn’t generally turn episodes over to lengthy ethical arguments; the very offbeat and experimental “Boom Town” comes the closest, but even that episode’s famed dinner debate scene takes up less than five minutes. The high point of “The Lazarus Experiment” comes in the cathedral, as the Doctor and Lazarus argue over the value of a single life. Gatiss allows us viewers little moments in which we might think we see the good in him, but then he invariably disappoints. Lazarus is an unrepentant narcissist, a man so convinced of his own godlike infallibility that he insists on calling his hideous transformations a sign of progress. The man can’t possibly believe that such a monster should represent the future of humanity, but if he is that monster, he’s willing to make an exception. Lazarus’ fear of death is so insane, so pathological that he believes even this hideous mutation constitutes a triumph. As he so proudly claims, he has gone further in the pursuit of immortality than any other human, and that enough justifies all the carnage that has led him to that point.

Again, that makes for a great few minutes of dialogue between David Tennant and Mark Gatiss, but “The Lazarus Experiment” needs some way to externalize its finer, more abstract points, some way to expand the story to 45 minutes, and that’s why the giant scorpion is required. It’s just that this is a particularly square peg being jammed into an exceedingly round hole. It’s not that the concept of the scorpion is ridiculous; I mean, it absolutely is, to the point that I’m not actually sure where I would even begin pointing out its ludicrousness. But the Carrionites in “The Shakespeare Code” were no less ridiculous. The difference there was that the entire story was built around the power of words, and a Shakespeare-focused story is the natural place to include some Macbeth-inspired witches. The internal logic of the Carrionites wasn’t flawless, but it roughly made sense, and it tracked well with the story’s thematic concerns; I could have done without the cackling and the broomstick, but those didn’t break the episode. For its part, the Lazarus scorpion could make sense if the story were more specifically about the perils of genetic engineering or something, but it’s an uneasy fit with a story about prolonging life. Perhaps “The Lazarus Experiment” does need a monster, but I wouldn’t say it needs this monster, especially when Mark Gatiss makes the human Lazarus far scarier anyway.

The one great advantage of such an intimidating threat is that it gives Martha a chance to play the hero alongside the Doctor, even if she does so over the vociferous objections of her mother. As we reach the midpoint of Martha’s season—even if she only technically becomes a companion at the very end of this episode—it’s worth taking stock of where she stands. “The Lazarus Experiment” reaffirms the impression of her that we got back in “Smith And Jones,” as Martha proves a cool, competent sidekick to the Doctor. Like any good companion, she knows which of the Doctor’s orders to follow and which to ignore, and she takes the lead in getting everyone out of the building while the scorpion is on the warpath. Her willingness to act as bait for Lazarus in the climax is tremendous proof of bravery, and it’s nice that her sister Tish also takes the chance to redeem herself after that rather regrettable business in which she considered romancing the revived Lazarus.

If there’s a flaw with Martha, it’s that she reads a little too much like a prefabricated companion. The first season of the new series spent a lot of time on developing Rose; that season argued that she had the natural qualities that made her worthy of the Doctor’s trip of a lifetime, but she needed the experiences on the TARDIS to help her move beyond her previously aimless existence. Understandably, Doctor Who doesn’t want to repeat all those same character beats with Martha, so it wisely positioned herself as someone much further along in her development. As a medical student and the only sane person in the Jones clan, Martha is plenty competent before she meets the Doctor. And that’s good, because the Doctor is prepared to show her the universe, but he quite explicitly keeps her at arm’s length; he isn’t interested in engaging with her and helping her become a better person.

The result is a relationship between Doctor and companion that is far shallower than the last such pairing. I don’t necessarily mean to compare Martha to Rose here, as this isn’t really about their inherent characters or how either is portrayed; indeed, a decent chunk of second season episodes didn’t really have much to say about Rose, leaning instead on the character’s previously established backstory. The whole point of the third season so far has been about how there just isn’t a spark between the Doctor and Martha, despite the fact that Martha quite clearly has some skills as a companion. All this should reflect negatively on the Doctor, but he’s so unquestionably the show’s hero that this doesn’t land properly. All this matters only if the development of the Doctor-companion relationship is a priority for the viewer, and I’ll admit that, generally speaking, I’m enough of an old-school fan that the Doctor and Martha’s relationship works fine as is. But the new series has made a point of saying that this relationship does matter. The lack of depth to this pairing has been a very conscious choice to this point as a specific reaction to the depth of the Doctor and Rose’s relationship, but I’m not sure this narrative choice has done the Doctor, Martha, or the show in general any favors. At the season’s midpoint, Martha works fine as a character in isolation, but neither the Doctor nor Doctor Who is entirely prepared to admit it. This surely can’t end well, but I suppose only time can tell on that point.

Stray observations:

The old-age makeup for Mark Gatiss looks halfway convincing. The only time it really works is right at the beginning during his press conference, a moment that gains a lot from the fact that he’s appearing on a blurry TV screen. It helps that we don’t see what Gatiss actually looks like until after his transformation. Again though, it’s really only as convincing as Gatiss’ performance, and there the episode once again benefits, as Gatiss is very, very good at playing a lecherous, creepy old man.

Adjoa Andoh does some nice work here as Francine Jones. It’s a tricky role, in that her main job is to be bossy and suspicious, but she does convey just enough maternal affection that it makes sense she would be worried about Martha’s welfare, albeit in a highly presumptuous sort of way. Stephen Greenhorn’s script only really hints at this, but we can infer from “Smith And Jones” that Francine is in a fragile place after her separation from her husband, and Andoh’s body language does suggest that she’s going through her own personal struggles that feed into her paranoia about the Doctor. As such, it only makes sense that Mr. Saxon’s agents would find her so easy to manipulate.

Just to return to my original point about monsters, I should say that the classic series was hardly immune from cramming in gratuitous monsters. Indeed, three of the all-time great stories from the original series feature such beasts. “The Talons Of Weng-Chiang” features giant rats that only barely make sense in terms of the mad science going on elsewhere, but they a necessary obstacle to pad out the story to six episodes. “Inferno” has a terrific story about parallel universes to tell, but the only way it can stretch out to seven episodes is by featuring the feral Primords, beasts that are only barely relevant to the central story. And “Caves Of Androzani,” which I’ve already mentioned as my all-time favorite Doctor Who story, features an utterly superfluous magma monster because it needed something to serve as a cliffhanger for episode two. It’s a rather weak cliffhanger, admittedly, but “Caves Of Androzani” does rather make up for it with the cliffhanger for episode three.

“Any number that reduces to one when you take the sum of the square of its digits and you continue iterating until it yields one is a happy number. Any number that doesn’t, isn’t. A happy prime is a number that is both happy and prime. Now type it in! I don't know, talk about dumbing down! Don't they teach recreational mathematics anymore?”

The worst thing I can say about “42” is that it isn’t “The Impossible Planet”/“The Satan Pit.” As the revived Doctor Who’s second foray into relatively hard, space-set science fiction, this episode can’t help but evoke comparisons with last season’s terrific two-parter. Indeed, there are times where “42” can feel like the previous story with the serial numbers filed off. The similarities range from deliberate callbacks—mostly notably the spacesuits, and the design of the S.S. Pentallian is meant to evoke the same future time period—to more general echoes in the narratives. Both stories feature cosmically incomprehensible enemies, possessed crewmembers, intentionally convoluted chase sequences, and even plot beats like the TARDIS getting lost behind a bulkhead as the situation worsens and the Doctor saving his companion as her would-be escape vessel plummets into a deadly celestial object. I’m overstating the parallels, to be sure, but the cumulative effect is that “42” is at its weakest when it is most directly in the shadow of its predecessor. The overriding successes of last season’s two-parter were in its characterization and its thoughtfulness; the double-length running time enabled “The Impossible Planet”/“The Satan Pit” to kick around complex—at least by Doctor Who standards—idea about religion and to develop the Sanctuary Base crewmembers as nuanced, multidimensional characters.

By contrast, those aboard the S.S. Pentallian are never much more than archetypes. Kath McDonnell is a tough but fair captain, a heartbroken wife, and a bit of a cheapskate when it comes to refueling. Riley Vashtee is the kind of unsurprisingly handsome, affable young crewman that you’d expect Martha to (almost) die beside. Dev Ashton and Erina Lessak have a combative working relationship. Abi Lerner is clever enough for the Doctor to comment approvingly. Orin Scannell is a survivor, in that he comes across as a bit of a pragmatist; besides, he’s one of just two crewmembers who survive the story, so he earns the title pretty much by default. It’s not that any of these are so terribly predictable or clichéd—Captain McDonnell is at least a reasonably novel combination of various familiar traits—but these are all thinly sketched characterizations, there only to serve the basic needs of the story.

But then, that’s by design. The episode’s title, beyond being an allusion to Douglas Adams’ The Hitchhiker’s Guide To The Galaxy, indicates the story’s real-time conceit, as the Doctor and Martha are given precisely the 42 minutes that comprise an episode’s running time to save the Pentallian and its crew. Wisely, neither writer Chris Chibnall nor director Graeme Harper overemphasize this aspect of the story; considering that 2007 represented the very peak of 24’s cultural relevance, it’s a small but most welcome miracle that this episode eschews pretty much any countdown-related gimmickry. Instead, there is simply a sense of urgency that permeates “42,” and a lot of that comes from how the Doctor is written and portrayed. It’s an accepted trope of Doctor Who that its protagonist can earn the trust of any group of strangers, no matter how preposterous his presence might be; in this case, as with “The Impossible Planet”/“The Satan Pit,” his and Martha’s appearance really does appear impossible to the crewmembers, considering their tremendous isolation. In the earlier story, the Doctor had time to ingratiate himself with the Sanctuary Base crew, who were glad of the opportunity to discuss their insane situation. Here, the Doctor doesn’t have the luxury of such opening pleasantries.

It’s exhilarating to watch the Doctor assume command of the situation by sheer force of personality, and David Tennant sells that de facto takeover through a performance that is equal parts forceful and frantic; every other line is delivered as he breaks into a run. In other stories, the Doctor can mess around before properly acknowledging the gravity of the situation, but here he is all business. Really, that’s a good descriptor for “42” in general, and this is the one area where I’d say it improves on aspects of “The Impossible Planet.” For all the success of last season’s two-parter, its initial episode had a slightly languid pace, as writers Matt Jones and Russell T. Davies gradually set up the various mysteries and character beats that would pay off far more forcefully in “The Satan Pit.” Chris Chibnall’s script, on the other hand, is nothing if not fiercely economical. “42” is crammed with incident: the pub quiz-fueled race through the ship, the various showdowns with the possessed Korwin and Ashton, the Doctor’s daring rescue of Martha and Riley, and his subsequent possession by the sentient Toraji Sun. Throughout, Graeme Harper gives the audience precious few moments to catch its collective breath, though he picks his spots expertly. The mostly silent separation of the escape pod from the Pentallian is a particularly brilliant sequence, as the episode’s loud, frenetic chaos suddenly gives way to the crushing realization that the Doctor and Martha have lost each other.

If anything, the episode could have lingered still longer on that separation scene, just to really drive home the precariousness of the TARDIS team’s situation. As it is, the next portion of the episode splits time between the Doctor’s daring rescue attempt and Martha’s growing realization that she isn’t going to make it out of this alive. The latter scenes represent the weakest section of “42,” as Freema Agyeman and William Ash aren’t quite able to elevate their big emotional scenes together, at least not to the extent that their farewell kiss feels properly earned. They bond because they are in close quarters, and their resultant understated attraction occurs where you would logically expect it to, but the whole thing feels perfunctory. New Doctor Who has had its companions ask characters about their lives so many times that it’s become something of a storytelling trope—one not quite as hallowed as the requisite monster, admittedly—and this example doesn’t find much new to say, even as the pair stare death in the face. Here, the character work is slightly undercut by the needs of the long-form storytelling. Martha can’t move far beyond the expected worries about her family never knowing her fate, as the episode needs her to keep calling her mother and further ensnaring herself in Harold Saxon’s plans, whatever they might be.

Still, these are minor imperfections. And honestly, this season of Doctor Who needed an episode like “42.” This is an episode defined above all by its competence; this is a story that shows up promptly, hits all its marks, and leaves with minimal fuss. The very best Doctor Who episodes aspire to more than what “42” offers, and I probably wouldn’t rate this story quite so highly if it had been the seventh episode of really any other season. But context does matter; while I definitely wouldn’t call this season bad, all of its previous episodes were at best qualified successes. “Gridlock” was brilliant but bonkers, “The Shakespeare Code” was charming in places but could never quite nail down the right comedic tone, and last week’s Dalek two-parter was... well, I know I like it considerably more than the average Doctor Who fan, and even I am not going to hold it up as anything other than the season’s biggest misfire to date. The closest antecedent for “42” is probably “Smith And Jones,” a similarly functional story that understands precisely what it needs to accomplish and gets the job done without fuss, but “42” proves superior because it derives so much energy from its tight pacing and dynamic direction. After so many weird experiments, it’s exhilarating to watch an episode that knows precisely what it wants to do and then does it all. Ideally, I’d want it to have slightly more ambitious goals, but I can wait a week for that.

Stray observations:

Before rewatching this episode, my recollection was that all of the pub quiz-style questions had to do with our contemporary history, and I was gearing up to discuss how silly a contrivance that is. As it turns out, only a single question deals with the 20th century; it’s still a bit of a big coincidence, but I’ll allow it as a way to facilitate the various phone calls home to Francine. Besides, the Doctor’s rant about happy primes is more than enough to justify that entire plot point. I don’t know about you, but I’m definitely in the mood for some recreational mathematics.

If anyone feels I’ve gone overboard with the comparisons to “The Impossible Planet”/“The Satan Pit,” I feel I should point out that this story actually did almost bring back the Ood, with the plan to have them get possessed again. I’d say “42” distinctly benefits from this revision, as the relationship between Captain McDonnell and her possessed husband Korwin proves to be one of the more emotionally resonant aspects of this episode, and I imagine the episode would have lost that element if it had subbed in the Ood.

Also, given Doctor Who’s penchant for the on-the-nose names—and here’s where I realize I almost forgot to mention how ridiculous it is that the previous episode’s mad scientist is actually called Dr. Lazarus—it might be surprising that this episode’s spaceship has the rather unremarkable name S.S. Pentallian. Well, the ship was originally to given the far more mythologically appropriate name S.S. Icarus, but this was changed when the production team learned of Danny Boyle’s sci-fi film Sunshine, which also involved a spaceship named Icarus slowly falling into the Sun.

Next week: We reach what may well be the apex of David Tennant’s run—scratch that, Russell T. Davies’ tenure as showrunner—double scratch that, maybe the whole damn new series—as we take a look at “Human Nature” and “Family Of Blood.”